Simple mail transfer protocol (“SMTP”) is used for e-mail communications between computers. Typical e-mail systems include one or more mail transfer agents (“MTAs”) and one or more mail delivery agents (“MDAs”). SMTP messages are passed through one or more MTAs to an MDA for final delivery processing. Each MTA communicates processing results back to the previous MTA in the chain of communication for post-processing.
E-mail messages may have more than one recipient. MTAs and MDAs process each recipient separately and processing results may vary for different recipients of the same message. MTAs issue one or more RCPT TO commands and receive responses for each command. RCPT TO responses can be used to communicate early per-recipient processing status, but most of the processing, such as committing to mailbox storage, is done after message data is received, which occurs later in SMTP communication.
It is with respect to these and other considerations that the disclosure made herein is presented.